Annually, grain farmers are faced with weeds, for example, ryegrass and radish, within their crops. Often, weeds cause huge production losses each harvest. Presently, herbicides are used to attempt to control weeds in techniques such as crop-topping: the late application of herbicides to prevent weed seed-set in crop. Crop-topping may reduce grain contamination, but will not increase yields. Herbicide resistance is also making the use of chemicals to control weeds increasingly ineffective.
Another method of weed control includes careful management of rotation of land use. This involves farming different produce, such as vegetative crop then livestock, on alternative areas of land. Rotation methods may also involve not farming on a particular land area for one or more seasons. Rotation methods can decrease the amount of profitable land available to a farmer in a year and may force the farming of less profitable material on the available land.
Mechanical control of weed seed has also been used by farmers during harvest with the use of attachments to harvesting machinery. When plant material, including grain and unwanted straw and weed material is harvested, the grain is separated from the unwanted waste and collected, while the waste is either spread onto the harvested land or compiled into windrows for burning or baling. Whilst the spreading technique is almost entirely useless for weed control, the windrows can be somewhat effective.
Burning windrows has the ability to destroy weed seeds but only if the temperature of the burn is high enough. If seeds are dropped to the earth from the harvester and an unacceptable amount of straw and other material covers the seed, the seeds are insulated somewhat from the burn and remain viable. Conversely, baling collects the dropped waste material and compiles it into bales for removal from the area and use as livestock feed, for example. However, if the ryegrass levels in the crop were significant, the baled material will have an unacceptable level of annual ryegrass toxicity (ARGT) for direct straw export. Rather, the bales may only be used for pellet production.
An existing accessory for a harvester, known as a chaff top, transports the chaff fraction of the waste material, which contains the greatest portion of weed seed, to be placed on top of the straw fraction within a windrow. Accordingly, effective burning can be achieved and seeds are rendered unviable. However, these accessories have been rarely used as they have been found to prevent the smooth flow of material through the harvester and cause frequent blockages.
The present invention attempts to overcome at least in part the aforementioned disadvantages of previous mechanical weed seed management systems and devices.